1. Field of the Invention
The present invention relates to a distance adjusting apparatus and method for adjusting a distance between a sensor portion and an object to be examined, and an object examining apparatus and method for examining an object using the distance adjusting apparatus and method. Particularly, the present invention relates to a distance adjusting apparatus and method, and an object examining apparatus and method, using terahertz (THz) electromagnetic radiation.
2. Description of the Related Background Art
In this specification, the terminology “terahertz (THz) radiation”, or the like is used for electromagnetic radiation in a frequency range between about 30 GHz and about 30 THz. In recent years, non-destructive sensing technology using terahertz radiation has been developed and searched. Technical fields using such terahertz radiation include imaging fields using safe see-through examining apparatuses in place of X-ray apparatuses. Further, development has also been made with respect to spectroscopic technology for acquiring absorption spectra and complex dielectric constants to examine characteristics, such as bonding condition, of substances, analytic technology for analyzing bio-molecules, estimating technology for estimating carrier concentration and mobility, and the like.
An apparatus for examining an object using terahertz radiation is disclosed in JP 08-320254 A. In this apparatus, an object is irradiated with terahertz radiation transmitted in a space, and characteristics of materials in the object are examined based on changes in transmission condition of terahertz radiation transmitted through the object. According to this technology, a see-through image of an object can be obtained by scanning the object two-dimensionally.
It is well known that terahertz radiation can propagate through a transmission line used for transmission of high-frequency radiation signals. A paper published in the Applied Physics Letters (“APL”), 88, 212511, 2006, discloses an examining apparatus for examining characteristics of an object in an on-chip manner in which an object is placed on the transmission line, using the above-described property of terahertz radiation. The sensor chip described in that paper uses a generator for generating terahertz radiation, a microstrip line, and a detector for detecting terahertz radiation, integrated on a glass substrate. In the APL article, attenuation in intensity of terahertz radiation and delay of time-domain waveform of terahertz radiation due to interaction between leaking electromagnetic field and water placed on the microstrip line are measured. The leaking electromagnetic field is an electromagnetic field that appears due to slight leakage of terahertz radiation from the microstrip line.
The above-described terahertz radiation examining systems using the sensor chip have the following disadvantages due to the use of on-chip examination.
These systems are not suited for measuring a large amounts or quantities of the objects being studied at high rate. For example, where the purpose is screening various bio-molecules, chemical substances, or the like, sufficient examination speed and economical cost are required as well as sufficient examination accuracy. In the conventional system, however, a considerable number of steps of supplying a sample, placing a chip on the examining apparatus, removing the chip therefrom, and the like are necessary, so that speedy examination is difficult to attain.
In addition, where a large number of samples are examined, the number of chips to be used must correspond to the number of samples. However, considering that semiconductor crystal is generally used to generate and detect terahertz radiation, it is likely that the examination cost will increase to a problematic degree as the number of chips increases.